JP2007232353A - Centrifugal compression refrigerator and lubricating oil used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compression refrigerator operable without hindrance even when using a 1,1,1,3,3-pentafluoropropane refrigerant. <P>SOLUTION: The compression refrigerator comprises: an evaporator 2; a condenser 1; a refrigerant; a compressor 3 compressing the refrigerant from the evaporator; a drive source 5 driving the compressor; lubricating oil; a lubricating oil system 7 for circulating the lubricating oil; and a refrigerant system 14 for circulating the refrigerant. The refrigerant is 1,1,1,3,3-pentafluoropropane, the compressor is a centrifugal compressor, and the lubricating oil contains at least one kind of polyester and polyether as a main component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a centrifugal compression refrigerator using 1,1,1,3,3-pentafluoropropane (R245fa) as a refrigerant, and a lubricating oil used therefor.

2. Description of the Related Art Conventionally, centrifugal compression refrigerators, so-called turbo refrigerators, are used for building cooling and heating, industrial cold water production plants, and the like. As refrigerants for centrifugal compression refrigerators, chlorofluorocarbons containing fluorine and chlorine, such as chlorofluorocarbon (CFC), such as R11, have been used. Its production and use have been regulated, and it has now been converted to new hydrogen-containing chlorofluorocarbon refrigerants that do not contain chlorine, such as tetrafluoroethane (R134 or R134a).
JP-A-6-221696

  As a refrigerant, tetrafluoroethane has an ozone depletion potential (ODP) of 0, but has a high global warming potential (GWP), so that 1,1,1,3,3-penta is a more environmentally friendly refrigerant. Fluoropropane (R245fa) has attracted attention.

  However, when a 1,1,1,3,3-pentafluoropropane refrigerant is used in a centrifugal compression refrigerator, there is a problem that it is not compatible with existing mineral oil-based refrigerator oil. The present invention solves such problems, and an object of the present invention is to provide a centrifugal compression refrigerator that can be operated without any trouble even when 1,1,1,3,3-pentafluoropropane refrigerant is used. Is to provide.

  As a result of diligent research in order to achieve the above object, the present inventors have found that a specific oxygen-containing compound is used when a 1,1,1,3,3-pentafluoropropane refrigerant is used in a centrifugal compression refrigerator. As a result, the present inventors have found that the operation of a refrigeration system comparable to the case of using a chlorofluorocarbon such as R11 or a hydrogen-containing fluorocarbon refrigerant such as tetrafluoroethane is possible by using a lubricating oil mainly composed of .

  A centrifugal compression refrigerator according to the present invention includes an evaporator, a condenser, a refrigerant, a compressor that compresses refrigerant from the evaporator, a drive source that drives the compressor, a lubricating oil, a lubricating oil system in which the lubricating oil circulates, And a refrigerant refrigeration system in which the refrigerant circulates, wherein the refrigerant is 1,1,1,3,3-pentafluoropropane, the compressor is a centrifugal compressor, and the lubricating oil is polyester and poly The main component is at least one kind of ether. The centrifugal compression refrigerator according to the present invention preferably includes an oil recovery system that returns the lubricating oil mixed in the refrigerant system to the lubricating oil system. The polyester is a compound containing a plurality of ester bonds, and typically includes a polyol ester, a diester, and a complex ester. The polyol ester is an ester synthesized from an acid and a polyhydric alcohol as raw materials, and usually a monovalent acid is used. The diester is an ester synthesized from an alcohol and a polyvalent acid as raw materials, and usually a monovalent alcohol is used. A complex ester is an ester synthesized from a polyvalent acid and a polyhydric alcohol as raw materials. Usually, the raw material contains a monovalent acid.

  The lubricating oil used in the centrifugal compression refrigerator according to the present invention includes an evaporator, a condenser, a refrigerant composed of 1,1,1,3,3-pentafluoropropane, a centrifugal compressor that compresses the refrigerant from the evaporator, A lubricating oil used in a centrifugal compression refrigerator having a driving source for driving a centrifugal compressor, a lubricating oil, a lubricating oil system in which the lubricating oil circulates, and a refrigerant system in which a refrigerant circulates, and at least one of polyester and polyether Mainly seeds.

The above-mentioned lubricating oil has a kinematic viscosity at 40 ° C. of 6 to 300 mm ² / s, and a polyester mainly composed of a polyol ester composed of a 2 to 6 valent polyhydric alcohol and a C 5 to 12 monovalent fatty acid. It is preferable. Moreover, the above-mentioned lubricating oil has a kinematic viscosity at 40 ° C. of 25 to 300 mm ² / s, and the polyester has 2 to 6 valent polyhydric alcohols, 3 to 18 monovalent fatty acids, and 4 to 14 carbon atoms. It is also preferable to use a complex ester of a polybasic acid as a main component. Furthermore, it is preferable that the mass ratio of the above-described lubricating oil and refrigerant is 90:10 to 10:90.

  As a lubricant for a centrifugal compression refrigerator using 1,1,1,3,3-pentafluoropropane (R245fa) as a refrigerant, a lubricant mainly composed of at least one of polyester and polyether is used. Therefore, even if a 1,1,1,3,3-pentafluoropropane refrigerant is used, it is compatible with the refrigerant without phase separation even at a sufficiently low temperature, and is chemically stable. As with conventional chlorofluorocarbon refrigerants, operation can be performed without hindrance.

[Centrifuge compression refrigerator]
An example of a centrifugal compression refrigerator is shown in FIG. The centrifugal compression refrigerator includes a condenser 1, an evaporator 2, a centrifugal compression compressor (turbo compressor) 3, and a drive source 5 that drives the compressor 3. The condenser 1 includes a heat transfer tube 1A for introducing cooling water from the outside in order to cool the high-temperature and high-pressure refrigerant, and the evaporator 2 includes a heat transfer tube 2A for taking out the cold water to the outside. The condenser 1, the evaporator 2 and the compressor 3 are connected by a refrigerant system 14, and an expansion valve 14 </ b> A is interposed between the condenser 1 and the evaporator 2.

  An oil tank 4 for storing lubricating oil is provided below the compressor 3, and an oil pump 6 for circulating the lubricating oil is provided in the oil tank 4. The lubricating oil system 7 is formed between the oil pump 6, the compressor 3, and the drive source 5, and has a structure for circulating the lubricating oil to the respective bearing portions 51A, 51B, 51C. The lubricating oil system 7 is provided with a moisture detector 9 and an oil cooler 10.

  The lubricating oil system 7 has an oil recovery function. An ejector 31 is interposed in the first oil recovery system 30 through which the lubricating oil circulates, and a partition valve 12, a moisture removing device 8, an oil strainer 11, and a valve 13 are interposed on the discharge side of the ejector 31. It has been returned to. Below the refrigerant liquid level of the evaporator 2 and near the refrigerant liquid level and the negative pressure generating part of the ejector 31 are connected by the second oil recovery systems 32 and 35 via the oil recovery unit 33.

  The heater 34 is for heating the refrigerant liquid in the oil recovery unit 33. The second oil recovery system 35 is provided at the bottom of the oil recovery unit 33, and further, a refrigerant recovery system 36 for recovering the refrigerant is provided at the top of the oil recovery unit 33. The refrigerant system 14 is connected between the evaporator 2 and the compressor 3.

  Next, the operation of the centrifugal compression refrigerator having the above configuration will be described. The high-temperature and high-pressure refrigerant gas compressed by the compressor 3 is introduced into the condenser 1, where it is cooled by the cooling water flowing through the heat transfer tube 1A and liquefied to become a liquid refrigerant. The low-temperature and high-pressure liquid refrigerant that has exited the condenser 1 is further lowered in temperature when passing through the expansion valve 14 </ b> A and becomes a low-temperature and low-pressure liquid refrigerant that accumulates in the evaporator 2. Here, for example, when the cold water that has returned to heat by exchanging heat with air by an external air conditioning load exchanges heat with the liquid refrigerant in the heat transfer tube 2A, the liquid refrigerant evaporates to become refrigerant gas. This refrigerant gas is compressed by the compressor 3 to become high-temperature and high-pressure refrigerant gas again and introduced into the condenser 1, where it is cooled by cooling water flowing through the heat transfer tube 1A and liquefied to become a liquid refrigerant.

  Near the level of the refrigerant in the evaporator 2, the lubricating oil leaking from the compressor 3 is separated from the refrigerant to form a lubricating oil layer on the refrigerant. Lubricating oil is taken from the lubricating oil layer into the oil recovery unit 33 via the oil recovery system 32. In the oil recovery unit 33, the refrigerant gas from the condenser 1 is passed through the piping of the heater 34, and the lubricating oil in the oil recovery unit 33 is heated by this heat to vaporize the mixed refrigerant, thereby increasing the concentration of the lubricating oil component. . On the other hand, the lubricating oil is sucked up from the oil collector 33 by the negative pressure generated in the ejector 31 from the oil collector 33 and returns to the oil tank 4.

[Refrigerant]
As the refrigerant, a refrigerant mainly composed of 1,1,1,3,3-pentafluoropropane (R245fa) is used. The content of 1,1,1,3,3-pentafluoropropane in the refrigerant is preferably 50% by mass or more, particularly preferably 90% by mass or more. As the other refrigerant to be mixed, a refrigerant having an ozone depletion coefficient (ODP) of 0 and a hydrogen-containing fluorocarbon refrigerant are preferable, and specifically, tetrafluoroethane (R134 or R134a) is preferable.

  The mass ratio of the lubricating oil and the refrigerant is preferably 90:10 to 10:90, particularly 50:50 to 10:90, and more preferably 30:70 to 10:90 from the viewpoint of the thermal efficiency of the system.

〔Lubricant〕
The lubricating oil is mainly composed of at least one of polyester and polyether, and is preferably composed of at least one of polyol ester, diester, polyether, and complex ester. It is preferable that these compounds are contained in a total of 80% by mass or more, particularly 90% by mass or more. Other components that can be included as the lubricant base oil include mineral oil-based refrigerating machine lubricant base oil. Here, when the lubricating oil is mainly composed of polyol ester, diester or polyether, in order to operate the refrigeration system properly and ensure high efficiency, the kinematic viscosity at 40 ° C. is 6 to 300 mm ² / s, In particular, the thickness is preferably ⁶ to 80 mm ² / s, more preferably 7 to 70 mm ² / s from the viewpoint of the thermal efficiency of the system. Moreover, when lubricating oil has complex ester as a main component, in order to operate a refrigeration system appropriately and to ensure high efficiency, kinematic viscosity in 40 degreeC is 25-300 mm < ² > / s, Especially 32-80 mm < ² >. / S, more preferably 32 to 70 mm ² / s, from the viewpoint of the thermal efficiency of the system. As base oils other than these compounds, mineral oils and synthetic oils generally used as lubricating base oils can be added as desired.

[Polyol ester]
As the polyol ester, an ester of a polyol having 3 to 20 diols or hydroxyl groups and a fatty acid having 6 to 20 carbon atoms is preferably used. Here, as the diol, specifically, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1, 3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12- And dodecanediol.

  Specific examples of the polyol having 3 to 20 hydroxyl groups include trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, -(Pentaerythritol), tri- (pentaerythritol), glycerin, polyglycerin (glycerin 2-20mer), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol Polyhydric alcohols such as mannitol, xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, Yukurosu, raffinose, gentianose, sugars and their partial etherification such as melezitose, and methyl glucoside (glycoside) and the like.

  Among these, as diol or polyol, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol) Hindered alcohols such as tri- (pentaerythritol) are preferred. In the diol or polyol to be used, the carbon number is not particularly limited, but usually those having 1 to 24 carbon atoms, preferably 2 to 12 carbon atoms, and further 4 to 8 carbon atoms are preferably used.

  In the fatty acid used in the polyol ester, the number of carbon atoms is not particularly limited, but those having 1 to 24 carbon atoms are usually used. Among fatty acids having 1 to 24 carbon atoms, those having 3 or more carbon atoms are preferable from the viewpoint of lubricity, those having 4 or more carbon atoms are more preferable, those having 5 or more carbon atoms are further preferable, and those having 7 or more carbon atoms. Is particularly preferred. Moreover, from a compatibility point with a refrigerant | coolant, a C18 or less thing is preferable, a C12 or less thing is more preferable, and a C9 or less thing is still more preferable.

  The fatty acid may be either a linear fatty acid or a branched fatty acid, but a linear fatty acid is preferable from the viewpoint of lubricity, and a branched fatty acid is preferable from the viewpoint of hydrolysis stability. . Specific examples of fatty acids include pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid , Nonadecanoic acid, icosanoic acid, oleic acid and the like, and these fatty acids may be either linear fatty acids or branched fatty acids, and furthermore, fatty acids having a quaternary carbon atom (neo Acid). Among these, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), pelargonic acid (n-nonanoic acid), caprin Acid (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid and 3,5,5 5-Trimethylhexanoic acid is preferably used.

  In addition, as long as it has two or more ester groups, the polyol ester according to the present invention may be a partial ester in which some of the hydroxyl groups of the polyol remain without being esterified. May be a complete ester esterified, and may be a mixture of a partial ester and a complete ester, but is preferably a complete ester. When the residual amount of carboxyl groups is large, the reaction with the metal used in the refrigerator produces metal soap and other undesired phenomena such as precipitation, so the total acid value is 3 mgKOH / g or less. Is preferable, and 0.1 mgKOH / g or less is more preferable. Also, if the residual amount of hydroxyl group is large, the ester becomes cloudy at low temperature and undesired phenomena such as clogging the capillary device of the refrigeration cycle occur. Therefore, the hydroxyl value is preferably 50 mgKOH / g or less, and 10 mgKOH / g The following are more preferable.

[Diester]
As the diester, an ester of a polybasic acid having 4 to 14 carbon atoms and an alcohol having 5 to 18 carbon atoms is preferably used. Specific examples of the polybasic acid include adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and terephthalic acid, and adipic acid, azelaic acid, and sebacic acid are preferable.

  Specific examples of the alcohol include 2-ethylhexanol, 3,5,5-trimethylhexanol, decyl alcohol, lauryl alcohol, oleyl alcohol and the like, and monohydric alcohols and 6 to 6 carbon atoms. Those having branches in 12 and particularly 8 to 10 hydrocarbon groups are preferred. Specifically, 2-ethylhexanol and 3,5,5-trimethylhexanol are preferable.

[Polyether]
The polyether is an organic compound having a plurality of ether bonds, and is typically represented by the following chemical formula 1 or chemical formula 2.

In the formula, each of R ^{1 to} R ⁵ represents hydrogen or an alkyl group having 1 to 8 carbon atoms, and each of A ^{1 to} A ³ represents ^{1 to} 2 or more of 5 to 300 alkylene oxide units having 2 to 4 carbon atoms. The constructed polymer chain is shown.

R ^{1 to} R ⁵ are each preferably hydrogen, a methyl group, an iso-propyl group, an iso-butyl group, or a tert-butyl group, and particularly preferably all of them are methyl groups. The alkylene oxide unit is preferably an ethylene oxide unit or a propylene oxide unit, and the polymer chain may be a block copolymer chain, a random copolymer chain or an alternating copolymer chain. The number of alkylene oxide units in the polymer chain is set so that the viscosity of the polyether falls within a predetermined range.

  Specific examples of the polyether include polyalkylene glycol or a derivative thereof, polyvinyl ether, and the like, and a polyalkylene glycol derivative or polyvinyl ether in which both ends are alkyl groups is preferable.

[Complex ester]
Complex esters include mixed acid esters of diols or polyols having 3 to 20 hydroxyl groups, particularly 2 to 6, and monovalent fatty acids having 3 to 18 carbon atoms and polybasic acids having 4 to 14 carbon atoms. Preferably used. Here, as the diol, specifically, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1, 3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12- And dodecanediol. The carbon number of the diol is preferably 4 to 12, particularly 4 to 10.

  Specific examples of the polyol having 3 to 20 hydroxyl groups include trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, -(Pentaerythritol), tri- (pentaerythritol), glycerin, polyglycerin (glycerin 2-20mer), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol , Polyhydric alcohols such as mannitol, xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, shuku Over scan, raffinose, gentianose, sugars and their partial etherification such as melezitose, and methyl glucoside (glycoside) and the like.

  Among these, diol or polyol includes neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol). Hindered alcohols such as tri- (pentaerythritol) are preferred. The number of carbon atoms in the polyol is preferably 3-15, particularly 5-10.

  In the monovalent fatty acid used for the complex ester, the carbon number is not particularly limited, but those having 3 to 24 carbon atoms, preferably 3 to 18 carbon atoms are usually used. Among monovalent fatty acids having 3 to 24 carbon atoms, those having 3 or more carbon atoms are preferable from the viewpoint of lubricity, those having 4 or more carbon atoms are more preferable, those having 5 or more carbon atoms, still more preferably 7 or more carbon atoms. Are particularly preferred. Moreover, from a compatibility point with a refrigerant | coolant, a C18 or less thing is preferable, a C12 or less thing is more preferable, and a C9 or less thing is still more preferable.

  The monovalent fatty acid may be either a linear fatty acid or a branched fatty acid, but is preferably a linear fatty acid from the viewpoint of lubricity, and a branched fatty acid from the viewpoint of hydrolysis stability. Is preferred. Specific examples of monovalent fatty acids include pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, Examples include octadecanoic acid, nonadecanoic acid, icosanoic acid, oleic acid, etc. These fatty acids may be either linear fatty acids or branched fatty acids, and furthermore, fatty acids having an α carbon atom that is a quaternary carbon atom. (Neo acid) may be used. Among these, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), pelargonic acid (n-nonanoic acid), caprin Acids (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid and 3,5,5 5-Trimethylhexanoic acid is preferably used.

  As the polybasic acid, those having 4 to 14 carbon atoms, particularly 6 to 12 carbon atoms are preferable, and divalent carboxylic acids are usually used. Specifically, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid , Azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid and the like, and adipic acid, azelaic acid, and sebacic acid are preferably used. The mass ratio of the polybasic acid and the monovalent fatty acid constituting the complex ester is preferably 10:90 to 90:10, particularly 50:50 to 70:30.

  In addition, as long as it has 2 or more ester groups, the complex ester concerning this invention may be a partial ester in which some of the hydroxyl groups which a polyol has remained without being esterified, and all hydroxyl groups May be a complete ester esterified, and may be a mixture of a partial ester and a complete ester, but is preferably a complete ester. When the residual amount of carboxyl groups is large, the reaction with the metal used in the refrigerator produces metal soap and other undesired phenomena such as precipitation, so the total acid value is 3 mgKOH / g or less. Is preferable, and 0.1 mgKOH / g or less is more preferable. In addition, if the residual amount of hydroxyl group is large, the ester becomes cloudy at low temperature and undesired phenomena such as blocking the expansion mechanism of the refrigeration cycle occur. Therefore, the hydroxyl value is preferably 50 mgKOH / g or less, and 10 mgKOH / g The following are more preferable.

[Lubricant additive]
For lubricating oil, various additives conventionally used in refrigerating machine oil, such as load-bearing additives, chlorine scavengers, antioxidants, metal deactivators, antifoaming agents, oiliness agents, antiwear additives An extreme pressure agent or the like can be blended.

  Load-bearing additives include monosulfides, polysulfides, sulfoxides, and other organic sulfur compounds, phosphate monoesters, phosphate diesters, phosphate triesters, phosphate esters, Phosphoric acid esters such as phosphoric acid monoesters and phosphorous acid diesters, thiophosphoric acid esters such as thiophosphoric acid triesters, fatty acid esters such as polyhydric alcohol esters and acrylic acid esters And fatty acid esters such as higher alcohols.

  Examples of the chlorine scavenger include glycidyl ether group-containing compounds, epoxidized fatty acid monoesters, epoxidized oils and fats, and epoxycycloalkyl group-containing compounds. Antioxidants include phenols (2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 4,4-methylene-bis- (2,6-di-tertiary). Butyl-p-cresol)), aromatic amines (α-naphthylamine, p, p′-di-octyl-di-phenylamine) and the like. Examples of the metal deactivator include benzotriazole derivatives. Examples of antifoaming agents include silicone oil (dimethylpolyoxane) and polymethacrylate.

  Hereinafter, the present invention will be described specifically by way of examples.

[Preparation of test oil]
The following 11 test oils were used. Sample oils a to c are examples of polyol esters, sample oil d is an example of diesters, sample oil e is an example of polyethers, and sample oils f to h are complexes. Examples of esters. As comparative examples, sample oils i to k were listed. Table 1 shows the kinematic viscosity, total acid value, and color of these test oils. The kinematic viscosity was measured by the ASTM color test method of JIS K 2283, the total acid value was JIS K 2501, and the color was JIS K 2580.

(Sample oil a) An ester of neopentyl glycol and 2-ethylhexanoic acid.
(Sample oil b) A mixture of 20% by mass of an ester of neopentyl glycol and 2-ethylhexanoic acid and 80% by mass of an ester of pentaerythritol and 2-ethylhexanoic acid.
(Sample oil c) Esters of pentaerythritol with a mixed acid of 50% by mass of 2-ethylhexanoic acid and 50% by mass of 3,5,5-trimethylhexanoic acid (sample oil d) Sebacic acid and 2-ethylhexanol And diester (dioctyl sebacate).
(Sample oil e) Polyether having a copolymer structure represented by CH ₃ —O— (PO) _m (EO) _n —CH ₃ . The molar ratio (m / n) of the oxypropylene group represented by (PO) and the oxyethylene group represented by (EO) is 8/2 and the average molecular weight is about 1000.
(Test oil f) A complex ester of neopentyl glycol and mixed acid (a mixture of 70% by mass of 3,5,5-trimethylhexanoic acid and 30% by mass of adipic acid).
(Sample oil g) Complex ester of trimethylolpropane and mixed acid (a mixture of 95% by mass of 3,5,5-trimethylhexanoic acid and 5% by mass of adipic acid).
(Test oil h) Complex ester of trimethylolpropane and mixed acid (a mixture of 90% by mass of 2-ethylhexanoic acid and 10% by mass of sebacic acid).

(Sample oil i) Refrigerating machine oil of naphthenic mineral oil (SUNISO 3GS manufactured by Nippon San Oil).
(Sample oil j) Linear alkylbenzene (Matsumura Oil Barrel Freeze).
(Test oil k) Branched alkylbenzene (Atmos manufactured by Nippon Oil Corporation).

[Evaluation of test oil]
Using R245fa as the refrigerant, the two-layer separation temperature and chemical stability of the test oil were evaluated. The two-layer separation temperature is determined according to JIS K 2211 Annex 3 “Compatibility Test Method with Refrigerant”, with an oil content of 10% by mass (oil / R245fa = 1/9) and an oil content of 20% by mass (oil / R245fa = The two-layer separation temperature of 2/8) was measured. For chemical stability, the color of the solution after 14 days at 175 ° C. was measured according to JIS K 2211 appendix 2 “Testing method for chemical stability with refrigerant”. These results are shown in Table 2.

  From Table 2, it can be seen that the test oils a to h are chemically stable because they do not phase-separate from the refrigerant even at a low temperature and the color after the chemical stability test does not change. .

  Even in the case where a 1,1,1,3,3-pentafluoropropane refrigerant is used in the centrifugal compression refrigerator, the operation can be performed without any trouble as in the case of a conventional fluorocarbon refrigerant.

It is the figure which showed an example of the centrifugal compression refrigerator.

Explanation of symbols

1 Condenser 2 Evaporator 1A, 2A Heat Transfer Tube 3 Centrifugal Compression Compressor (Turbo Compressor)
4 Oil tank 5 Drive source 6 Oil pump 7 Lubricating oil system 8 Moisture removal device 9 Moisture detector 10 Oil cooler 11 Oil strainer 12 Partition valve 13 Valve 14 Refrigerant system 14A Expansion valve 30, 32, 35 Oil recovery system 31 Ejector 33 Oil Recovery unit 34 Heater 36 Refrigerant recovery system 51A, 51B, 51C Bearing part

Claims (7)

  Compressor comprising an evaporator, a condenser, a refrigerant, a compressor that compresses the refrigerant from the evaporator, a drive source that drives the compressor, a lubricating oil system that circulates the lubricating oil, and a refrigerant system that circulates the refrigerant In the refrigerator, the refrigerant is 1,1,1,3,3-pentafluoropropane, the compressor is a centrifugal compressor, and the lubricating oil is mainly composed of at least one of polyester and polyether. A centrifugal compression type refrigerator characterized by that. The lubricating oil according to claim 1 is mainly composed of a polyol ester having a kinematic viscosity at 40 ° C. of 6 to 300 mm ² / s and a polyester comprising a 2 to 6 valent polyhydric alcohol and a 5 to 12 carbon monovalent fatty acid. The centrifugal compression refrigerator according to claim 1, wherein the centrifugal compressor is a component. The kinematic viscosity at 40 ° C. of the lubricating oil according to claim 1 is 25 to 300 mm ² / s, the polyester is a 2 to 6 valent polyhydric alcohol, a 3 to 18 carbon monovalent fatty acid, and a 4 to 14 carbon atom. The centrifugal compression refrigerator according to claim 1, characterized in comprising a complex ester of polybasic acid as a main component.   The centrifugal compression refrigerator according to claim 1, wherein the mass ratio of the lubricating oil and the refrigerant according to claim 1 is 90:10 to 10:90.   Evaporator, condenser, refrigerant composed of 1,1,1,3,3-pentafluoropropane, centrifugal compressor for compressing refrigerant from the evaporator, drive source for driving this centrifugal compressor, lubricating oil, lubricating oil Is a lubricating oil used in a centrifugal compression refrigerator having a lubricating oil system in which the refrigerant circulates and a refrigerant system in which the refrigerant circulates, the centrifugal compression type having at least one of polyester and polyether as a main component Lubricating oil used in refrigerators. The lubricating oil according to claim 5 is mainly composed of a polyol ester having a kinematic viscosity at 40 ° C. of 6 to 300 mm ² / s and a polyester comprising a 2 to 6 valent polyhydric alcohol and a 5 to 12 carbon monovalent fatty acid. The lubricating oil used for the centrifugal compression refrigerator according to claim 5, wherein the lubricating oil is a component. The lubricating oil according to claim 5 has a kinematic viscosity at 40 ° C of 25 to 300 mm ² / s, the polyester is a 2 to 6 valent polyhydric alcohol, a 3 to 18 monovalent fatty acid, and a 4 to 14 carbon number. 6. The lubricating oil used for a centrifugal compression refrigerator according to claim 5, comprising a complex ester of a polybasic acid as a main component.

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